What question did this study set out to answer?

To determine whether altered intracellular calcium handling or enhanced myofilament calcium sensitivity in mesenteric resistance arteries contributes to elevated blood pressure in spontaneously hypertensive rats.

January 1, 1995Hypertension

Myofilament Calcium Sensitivity of Normotensive and Hypertensive Resistance Arteries

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To determine whether altered intracellular calcium handling or enhanced myofilament calcium sensitivity in mesenteric resistance arteries contributes to elevated blood pressure in spontaneously hypertensive rats.
Simultaneously measured intracellular calcium and isometric force in endothelium-denuded mesenteric resistance arteries from 12- to 15-week-old male SHR, WKY, and Wistar rats.
Evaluated myofilament calcium sensitivity using cumulative extracellular calcium additions (0.025 to 2.5 mmol/L) under 100 mmol/L potassium or 10 μmol/L norepinephrine following intracellular store depletion.
Tested vascular responses during cumulative norepinephrine stimulation in the presence of constant physiological extracellular calcium (1.5 mmol/L).
Basal intracellular calcium did not differ significantly among strains (SHR: 86.6±4.5 nmol/L; WKY: 78.5±4.7 nmol/L; Wistar: 83.1±3.9 nmol/L), and 100 mmol/L potassium revealed no strain differences in stress or calcium sensitivity.
Under 10 μmol/L norepinephrine after calcium depletion, SHR vessels showed increased myofilament calcium sensitivity compared with WKY and Wistar controls (P < .05; ED25: 74.4±5.1 nmol/L for SHR vs 89.8±5.5 nmol/L for WKY and 86.9±3.4 nmol/L for Wistar).
During cumulative norepinephrine exposure with constant extracellular calcium (1.5 mmol/L), intracellular calcium and active stress responses did not differ between SHR and WKY vessels.

Structured PICO

Population

Endothelium-denuded mesenteric resistance arteries of 12- to 15-week-old male spontaneously hypertensive rats (SHR), Wistar-Kyoto (WKY) rats, and Wistar rats

Intervention

Cumulative addition of extracellular Ca2+ (0.025 to 2.5 mmol/L) in the presence of 100 mmol/L K+ or 10 μmol/L norepinephrine after depletion of releasable intracellular Ca2+ stores, and cumulative addition of norepinephrine with constant extracellular Ca2+ (1.5 mmol/L)

Comparator

Normotensive Wistar-Kyoto (WKY) and Wistar rats

Outcome

Intracellular Ca2+ and isometric force (myofilament Ca2+ sensitivity)surrogate

Enhanced myofilament Ca2+ sensitivity is unlikely to contribute to the hypertension of spontaneously hypertensive rats, as differences are not observed under physiological conditions.

Discussion

No takes yet. Share an insight, caveat, or question.

Implication

Unlikely to contribute to SHR hypertension under physiological conditions; challenges this mechanism and directs research to alternative pathways.

Cite This Study

Bian et al. (1995) studied this question.

synapsesocial.com/papers/6a757e09b1c5cc4eb2b1c4cc https://doi.org/10.1161/01.hyp.25.1.110

Topics

Hypertension management

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Implication

Unlikely to contribute to SHR hypertension under physiological conditions; challenges this mechanism and directs research to alternative pathways.

Myofilament Calcium Sensitivity of Normotensive and Hypertensive Resistance Arteries

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

Myofilament Calcium Sensitivity of Normotensive and Hypertensive Resistance Arteries

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

Also Consider